Question

The perimeter of an isosceles triangle is 15.6m. Find the lengths of its sides, if:

The base is 3m bigger than a leg

Answer 1

Legs are 4.2m long.

Base is 7.2m long

Explanation:

x = leg

y = base

We can write 2 equations with the info given

y = x + 3

2x + y = 15.6

We can solve this as a system of equations.

y = x + 3

-(2x + y = 15.6) --- make the bottom equation negative

-2x = x - 12.6 --- add the bottom to the top, canceling out the y

-2x + 12.6 = x --- add 12.6 to both sides

12.6 = 3x --- add 2x to both sides

4.2 = x --- divide both sides by 3

x = 4.2

Now we can solve for y.

y = x + 3

y = (4.2) + 3 --- substitute in the x

y = 7.2 --- simplify

Check our answer.

2x + y = 15.6

2(4.2) + 7.2 = 15.6

8.4 + 7.2 = 15.6

15.6 = 15.6

The answer is correct